Short communication: Prevalence of Staphylococcus aureus and methicillin-resistant S. aureus in bulk tank milk from dairy goat farms in Northern Italy

Abstract

Staphylococcus aureus is regarded as a leading cause of mastitis in goats. However, few data are available on the presence of methicillin-resistant S. aureus (MRSA) in this species. The aim of this study was to assess the prevalence of S. aureus and MRSA in bulk tank milk samples from dairy goat farms in Northern Italy. Eighty-five out of 197 samples (43.1%) tested positive for S. aureus with counts ranging from 10 to more than 1.5 × 10(4) cfu/mL. The MRSA was screened by both direct plating followed by a disk diffusion test to evaluate methicillin resistance and a selective enrichment method. Methicillin-resistance was confirmed by mecA-specific PCR. Methicillin-resistant S. aureus was identified in 4 samples (2.0%) and multilocus sequence typing (MLST) showed the presence of livestock-associated MRSA belonging to lineages ST398 (n = 3) and ST1 (n = 1). In one case we demonstrated that the same MRSA strain was able to persist over time on the farm, being isolated from both bulk tank milk and the udder of 3 goats 1 yr after the first isolation. The high prevalence of S. aureus-positive herds detected in this study and the presence of MRSA strains belonging to livestock-associated genotypes is of concern, and represents a novel finding in the Italian dairy goat production system. The application of stringent measures for the control of S. aureus mastitis at the farm level seems appropriate to reduce the economic losses, and to minimize the risk of foodborne illness and the transmission of MRSA to humans by occupational exposure.

Occurrence and antibiotic resistance of enterotoxigenic Staphylococcus aureus in raw ovine and caprine milk in Greece

“…Similar to our results, S. aureus was detected in 24% of the raw OM samples collected from Epirus, Greece (Fotou et al 2011), whereas all milk samples collected from 21 sheep farms from the regions of Xanthi and Evros were positive for S. aureus . The data regarding the prevalence of S. aureus in CM and OM from other countries are also quite variable (Mørk et al 2003;Jørgensen et al 2005;de Garnica et al 2013;Spanu et al 2013;Cortimiglia et al 2015). Although differences in the sensitivity and specificity of the protocols used for bacterial isolation may have contributed to these variant results, the different husbandry practices applied in different countries may at least partly account for the aforementioned differences in prevalence estimates.…”

“…In our study, the MRSA isolate was resistant to AK, NN, FOX, DA, and E. Cortimiglia et al (2015) reported that three out of four MRSA isolates from bulk CM were resistant to TE, besides being resistant to penicillin and FOX. In addition, two of them were resistant to trimethoprim and one to DA.…”

“…According to Ridom Spa Server, the global frequency of occurrence of t4038 is low and has been reported in the Netherlands. More frequently, other MRSA spa types seem to be associated with raw milk, dairy products, and farm personnel such as t127 (Carfora et al 2015;Cortimiglia et al 2015), t899 (CC398) (Cortimiglia et al 2015), t011 (CC398), t567, and t108 (Bardiau et al 2013) and spa types t011, t034, and t2576 (Fessler et al 2010). Despite the fact that the spa type detected in our study is not among those associated with increased virulence in humans, typing of MRSA isolates can provide useful data on the epidemiology and monitoring of MRSA in foods.…”

Molecular Epidemiology of Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus in the Ovine Dairy Chain and in Farm-Related Humans

“…In Italy, the community-acquired MRSA (CA-MRSA) ST(CC) 1 spa -type t127 is reported among the main lineages of MRSA isolated in livestock productions [15,16,17,18,19,20,21]. CA-MRSA clones often harbor the PVL virulence genes, more than CA-MSSA, suggesting that methicillin resistance has contributed to the success of pvl -positive S. aureus strains [22].…”

Indirect diagnostic tests for the detection of subclinical mastitis in dairy goats experimentally infected with Staphylococcus aureus

“…The most frequent isolates are S. aureus, in clinical cases, and coagulasenegative species (CNS), in subclinical cases of intramammary infection (IMI) (BERGONIER et al, 2003). Control measures for S. aureus mastitis are important in order to reduce economic losses and decrease the risk of diseases, being transmitted to humans via food (CORTIMIGLIA et al, 2015). For instance, these authors recorded a high prevalence of S. aureus in herds of dairy goats by isolating methicillin-resistant strains (MRSA).…”